Phosphorus and its oxygen compounds
Answers are for parents and teachers.
1
How many grams of P₂O₅ form when 62 g (2 mol) of phosphorus burns (M(P₂O₅) = 142, 4P + 5O₂ → 2P₂O₅)?
142 g
2
How many electrons are transferred in total in 6P + 5KClO₃ → 5KCl + 3P₂O₅ (6P × 5e⁻)?
30
3
Calculate Mᵣ of Ca(H₂PO₄)₂. Aᵣ: Ca 40, H 1, P 31, O 16.
234
4
H₃PO₄ + 3NaOH → Na₃PO₄ + 3H₂O: how many grams of NaOH are needed for 196 g H₃PO₄?
240 g
5
Why do toothpastes contain fluorine compounds?
Hydroxyapatite in enamel turns into fluorapatite, which resists the acids that cause decay better.